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CVE-2026-53130· NVD / CVE Program· CNA Linux

fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

In the Linux kernel, the following vulnerability has been resolved: fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START omfs_fill_super() rejects oversized s_sys_blocksize values (> PAGE_SIZE), but it does not reject values smaller than OMFS_DIR_START (0x1b8 = 440). Later, omfs_make_empty() uses sbi->s_sys_blocksize - OMFS_DIR_START as the length argument to memset(). Since s_sys_blocksize is u32, a crafted filesystem image with s_sys_blocksize < OMFS_DIR_START causes an unsigned underflow there, wrapping to a value near 2^32. That drives a ~4 GiB memset() from bh->b_data + OMFS_DIR_START and overwrites kernel memory far beyond the backing block buffer. Add the corresponding lower-bound check alongside the existing upper-bound check in omfs_fill_super(), so that malformed images are rejected during superblock validation before any filesystem data is processed.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jun 24, 2026
Updated
Aug 5, 2026
EPSS
0.2% · 8th percentile
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JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Affected systems

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.27 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.141
  • linux linux kernel6.7 and later · before 6.12.91
  • linux linux kernel6.13 and later · before 6.18.33
  • linux linux kernel6.19 and later · before 7.0.10

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.27affected
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before fbc72f5c645155dc2ed3573243ed20f9913e3a54affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 5822a05a841a10794ad818620dd2af490b0705d3affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 754ff1bea3819a90c6f33cccfc1a299ef7609f07affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 131ea3e57fc22936ed0e2c8330f2e36106172f51affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 79f84af38c9fef9deb0e02c79eb969b5541c2644affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 6561afc38398e3518a29c5eebb975c30468f98a6affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 817f16ed62bc58a168417bfb5e859c2a370bab03affected · git
    • a3ab7155ea21aadc8a4d5687e91b3d876973185e and later · before 0621c385fda1376e967f37ccd534c26c3e511d14affected · git
    • before 2.6.27not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.10-17.0.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now
  • CVE-2019-13272In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to creKEV
    77This week
  • CVE-2013-6282The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the v6k and v7 ARM platforms do not validate certain addKEV
    77This week
  • CVE-2013-2094The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9 uses an incorrect integer data type, which allows loKEV
    77This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0621c385fda1376e967f37ccd534c26c3e511d14Vendor (CNA)
Linux Linux131ea3e57fc22936ed0e2c8330f2e36106172f51Vendor (CNA)
Linux Linux5822a05a841a10794ad818620dd2af490b0705d3Vendor (CNA)
Linux Linux6561afc38398e3518a29c5eebb975c30468f98a6Vendor (CNA)
Linux Linux754ff1bea3819a90c6f33cccfc1a299ef7609f07Vendor (CNA)
Linux Linux79f84af38c9fef9deb0e02c79eb969b5541c2644Vendor (CNA)
Linux Linux817f16ed62bc58a168417bfb5e859c2a370bab03Vendor (CNA)
Linux Linuxfbc72f5c645155dc2ed3573243ed20f9913e3a54Vendor (CNA)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-531761 days apartIB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN
    39Monitor
  • CVE-2026-4318749 days apartxfs: delete attr leaf freemap entries when empty
    35Monitor
  • CVE-2026-531781 days apartstaging: rtl8723bs: rtw_mlme: add bounds checks before ie_length subtraction
    32Monitor
  • CVE-2026-529190 days apartbatman-adv: fix tp_meter counter underflow during shutdown
    31Monitor
  • CVE-2026-4610727 days apartdm-thin: fix metadata refcount underflow
    31Monitor
  • CVE-2026-6436131 days aparthfs/hfsplus: fix u32 overflow in check_and_correct_requested_length
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-191 · Integer Underflow (Wrap or Wraparound)

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records